In recent years, responding to a demand of reduction of expenses and time for business trips, television conference systems have spread as an example of a transmission system that conducts a television conference via a communication network, such as the Internet. In such a television conference system, the various types of data, for example image data and audio data are transmitted/received between the television conference terminals as an example of transmission terminal to realize the television conference.
Furthermore, in the conventional television conference system, control associated with start or termination of communication among the television conference terminals is executed using a transmission management system (see Patent Document 1 Japanese Patent Application Laid-Open Publication No. 2012-50063, which is incorporated herein by reference in its entirety). In this case, the transmission management system establishes, when receiving a request of the start of communication from a television conference terminal, a session that transmits/receives the data among the television conference terminals by the control associated with start of communication. The transmission management system that has executed the control can control the state of the television conference terminals by updating the state of a requestor television conference terminal of the start of communication during the communication, for example.
However, conventionally related transmission system executes the control associated with the start or termination of communication in one transmission management system. Therefore, if a lot of the start of communication occur at the same time, the single transmission management system should control a plurality of connections between the transmission terminals and the relay devices. As a result, that leads significantly increase of the load applied to the one transmission management system. In a case where a plurality of transmission management systems is provided in order to disperse the loads, when one transmission management system has executed control associated with communication to change the state of a transmission terminal, another transmission management system cannot manage the state of the transmission terminal.